Multiplayer in Reach is 10x better. Not sure how many people you'll still find playing on Reach, but you'll get frustrated with Halo 4 Multiplayer quickly.

As somebody who's been playing Halo since November 2001 and played embarrassing amounts of Halo 2 Multiplayer, I have to say that both Reach and H4's MP are equally shitty in their own way. The series started going downhill with Halo 3, and has gotten worse with each successive title.